Hey Pete,
Check out the JPG I have attached. I think it should explain the situation quite nicely. I hope it helps!!
---First Set the access - such as what I have outlined below. (you must be at least REGISTERED to be able to upload)
Oh, almost forgot, when the admin creates the gallery, he/she MUST make it shareable".
1. User logs in and clicks on USER SYSTEM from the Gallery page
2. Click on the "upload files" link (you can also get here through the USER MENU)
3. Click on multiple files (or you can use other methods if you want) and then choose a gallery - NOTE: the gallery should be created by an admin unless you choose to allow access for a user to create a gallery but keep in mind that if a user creates a gallery, they can also delete it)
4. Notice that only the images this user uploaded will be able to be edited and deleted. Other user images are not available for editing.
